In a prior art design of such elastic clamps, the clamping spring is a closed or even intertwined design as, for example, found in German utility model DE 295 14 509 U1. This makes the clamping spring expensive to manufacture, and installation is difficult because the overlapping or engaging end sections of the clamping spring make it difficult to join with the busbar, especially inserting the busbar tongue through the window in the relevant end leg.